import {heightAtLine} from "../line/spans.js"
import {getLine, lineAtHeight, updateLineHeight} from "../line/utils_line.js"
import {paddingTop, charWidth} from "../measurement/position_measurement.js"
import {ie, ie_version} from "../util/browser.js"

// Read the actual heights of the rendered lines, and update their
// stored heights to match.
export function updateHeightsInViewport(cm) {
    let display = cm.display
    let prevBottom = display.lineDiv.offsetTop
    for (let i = 0; i < display.view.length; i++) {
        let cur = display.view[i], wrapping = cm.options.lineWrapping
        let height, width = 0
        if (cur.hidden) continue
        if (ie && ie_version < 8) {
            let bot = cur.node.offsetTop + cur.node.offsetHeight
            height = bot - prevBottom
            prevBottom = bot
        } else {
            let box = cur.node.getBoundingClientRect()
            height = box.bottom - box.top
            // Check that lines don't extend past the right of the current
            // editor width
            if (!wrapping && cur.text.firstChild)
                width = cur.text.firstChild.getBoundingClientRect().right - box.left - 1
        }
        let diff = cur.line.height - height
        if (diff > .005 || diff < -.005) {
            updateLineHeight(cur.line, height)
            updateWidgetHeight(cur.line)
            if (cur.rest) for (let j = 0; j < cur.rest.length; j++)
                updateWidgetHeight(cur.rest[j])
        }
        if (width > cm.display.sizerWidth) {
            let chWidth = Math.ceil(width / charWidth(cm.display))
            if (chWidth > cm.display.maxLineLength) {
                cm.display.maxLineLength = chWidth
                cm.display.maxLine = cur.line
                cm.display.maxLineChanged = true
            }
        }
    }
}

// Read and store the height of line widgets associated with the
// given line.
function updateWidgetHeight(line) {
    if (line.widgets) for (let i = 0; i < line.widgets.length; ++i) {
        let w = line.widgets[i], parent = w.node.parentNode
        if (parent) w.height = parent.offsetHeight
    }
}

// Compute the lines that are visible in a given viewport (defaults
// the the current scroll position). viewport may contain top,
// height, and ensure (see op.scrollToPos) properties.
export function visibleLines(display, doc, viewport) {
    let top = viewport && viewport.top != null ? Math.max(0, viewport.top) : display.scroller.scrollTop
    top = Math.floor(top - paddingTop(display))
    let bottom = viewport && viewport.bottom != null ? viewport.bottom : top + display.wrapper.clientHeight

    let from = lineAtHeight(doc, top), to = lineAtHeight(doc, bottom)
    // Ensure is a {from: {line, ch}, to: {line, ch}} object, and
    // forces those lines into the viewport (if possible).
    if (viewport && viewport.ensure) {
        let ensureFrom = viewport.ensure.from.line, ensureTo = viewport.ensure.to.line
        if (ensureFrom < from) {
            from = ensureFrom
            to = lineAtHeight(doc, heightAtLine(getLine(doc, ensureFrom)) + display.wrapper.clientHeight)
        } else if (Math.min(ensureTo, doc.lastLine()) >= to) {
            from = lineAtHeight(doc, heightAtLine(getLine(doc, ensureTo)) - display.wrapper.clientHeight)
            to = ensureTo
        }
    }
    return {from: from, to: Math.max(to, from + 1)}
}
